Hypercalcemia

Malignancy is the most common cause of severe hypercalcemia resulting in AMS. Malignancies most likely to cause hypercalcemia are breast cancer (30% to 40%), multiple myeloma (20% to 40%), squamous cell carcinomas of the lung (12% to 35%), the head, neck, or esophagus (19%), non-Hodgkin's lymphoma (3% to 13%), leukemias (2% to 11 %), renal cell carcinoma (8%), cervical carcinoma (7%), and colon cancer (5%). Of these, the only malignancies that commonly present initially with signs of hypercalcemia are adult T-cell lymphoma (45%) and multiple myeloma. Although hyperparathyroidism is a more common cause of hypercalcemia, most patients with that disorder have less severe hypercalcemia and are asymptomatic. Hypercalcemic crisis is usually defined as a serum calcium concentration >14 mg/dl with acute signs and symptoms.

Causes

Primary hyperparathyroidism is the most common cause of hypercalcemia over all and is the most common cause of excess PTH. High PTH causes the excess of calcium seen in familial hypocalciuric hypercalcemia a condition of benign hypercalcemia. The drug lithium used in treating bipolar disorder may increase PTH release and cause hypercalcemia.

• A tumor excessively producing PTH-rP. Such as tumors includeing lymphoma, anal sac carcinoma, mammary tumors, and multiple myeloma. It is possible for other tumors to secrete PTH-rP in high amounts but it is rare. The common tumors should be sought first. Lymphoma is probably the most common cause of elevated calcium by far.
• Parathyroid gland tumor secreting PTH.
• Malignancy
• Diuretics
• Parathyroid
• Immobilization
• Megadoses of vitamins A,D

Symptoms

Although symptoms are determined by both the absolute serum calcium concentration and the rate of rise, certain generalizations apply (Table 22-2).

• Polyuria and polydipsia ++++ due to inhibition of ADH
• Nausea and vomiting

Signs

• Evidence of extreme dehydration: dry mucous membranes, tachycardia, and orthostasis
• Increased vascular tone may lead to normal blood pressures despite severe dehydration.
• Coma, if present, usually occurs at concentrations > 15mg/dl.

Treatment

In mild to moderate elevations of calcium some treatment options may be available in the Emergency Department.

• Adequate hydration
• Stabilization and reduction of the calcium level
• Increased urinary calcium excretion
• Inhibition of osteoclast activity in the bone
• Discontinuation of pharmacologic agents associated with hypercalcemia